|I assumed (wrongly?) that you had got one of those bogus pop-ups that suddenly arrive saying you have a stack of viruses. MalwareBytes freebie can usually fix those and many others. I keep it onboard for manual use in case I get hit by something similar.|
I don't know much about Stopzilla but I believe they are authentic.
McAfee doesn't seem to get very good vibes on this forum but to be fair to them there is always a chance that one AV will find something that another will miss. As you probably know, you should only have one AV running in the background at any one time. Anything else should be an additional tool to scan the system manually if you suspect you are infected.
The most popular AV's on here (all free) seem to be:
Microsoft Security Essentials.
Avast (free version).
AVG (free) - rather bulky.
I have used all three. Avira is sometimes mentioned too but I have no experience of that one.
We all live on a ball.